Process of purifying gases produced by the gasification of solid or

Abstract

A process of purifying gases produced by a gasification of fossil fuels wherein the gas is cooled and scrubbed under superatmospheric pressures at normal temperatures while the raw gas, at a temperature of 150.degree.-170.degree. C, is indirectly cooled to ambient temperatures, the condensible hydrocarbons are separated and removed, the gas is scrubbed with water to remove ammonia in a first scrubbing stage in which the rate of water addition is controlled to be just sufficient to remove the ammonia, the gas is then scrubbed with a high-boiling organic solvent which is miscible with water and to which sulfur is added, the gas is subsequently scrubbed with the same solvent in a third scrubbing stage in which the water content of the solvent is kept at 5-30 mole percent H.sub.2 O and in which H.sub.2 S and COS are entirely removed from the gas, and the scrubbing agents from the second and third scrubbing stages are separately regenerated and recycled to the second and third scrubbing stages. The scrubbing agent used in the second scrubbing stage is flashed approximately to atmospheric pressures, adding water, heating the scrubbing agent to the boiling temperature but not in excess of 170.degree. C, treating the scrubbing agent in a stripping column with water vapor or stripping gas to remove liquid impurities, condensing the mixed vapors, isolating the condensates by phase separation, and feeding part of the aqueous phase as a reflux to the upper portion of the stripping column while the stripped scrubbing agent is cooled and is fed back to the top of the second scrubbing stage.